The Expansion of the Universe Wasn't Slowing Down, It Was Accelerating

In 1998, two teams of astronomers found that the expansion of the universe wasn't slowing down. Instead it is accelerating its rate of expansion - a 'phenomenal discovery' They looked at the luminosity and brightness of type 1A supernovas. These are white dwarfs less than 1.38 times the mass of the Sun. The gravitational force is so great as to overcome what's known as the electron degeneracy pressure. This causes them to collapse in on itself into a neutron star which turns into a supernova.